The function of valves in internal combustion engines is related to the precise timing of the opening of the intake valve in relation to the opening of the exhaust valve at given points in the location of the piston, be it at the bottom or at the top of the cylinder. To permit the outflow of gases the exhaust valve begins to open at the end of the third stroke and remains open during the entire fourth stroke, at which point the intake valve begins to open before the first stroke. The instant during which both valves are open is designated "overlap" or "timing " in this description.
In the systems of the prior art, based on twin or dual overhead camshafts, in order to vary the overlap of an intake valve in respect to an exhaust valve, it is necessary to change, the angular placement (in vertical plane) of one of the camshafts with respect to the other. Once the change is accomplished the new valve overlap remains fixed.
There are known devices for changing the "overlap" or "timing " through rotation of camshafts while the engine is in operation. However, such devices are very sophisticated and are currently applied only in high-performance engines.
On the other hand, the double effect distribution sequential valve shaft system ("SVS") admits the same rotation through a variator mechanism which is embodied in the present invention.
In addition, this invention modifies the opening section, as more fully described below, to enlarge or reduce the space through which the gases will flow in the distribution system. In the prior art, the enlargement of valve area occurs only by depressing the valve deeper, which has proven to cause serious difficulties in the behavior of cams and springs.